Chris Cooper
Active Member
Is it possible to retrofit a crotch strap to an RV3A? I?m used to a fifth strap and my head is quite close to the canopy.
Van's Air Force
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Retro fit crotch strap to RV3A
- Thread starter Chris Cooper
- Start date
Is it possible to retrofit a crotch strap to an RV3A? I?m used to a fifth strap and my head is quite close to the canopy.
My RV-3B has a doubler plate riveted to the bulkhead where the front of the seat pan ends. Looks like you'd have to drill out the pop rivets holding the seat pan in place to get to it. Probably has a 1/4" nut plate on the rear side of that bulkhead.
Finn
Since the crotch strap mainly keeps you from submarining forward in a crash, I would think that you could just create a strap, wide enough to catch two rows of rivets on the seat pan, that is bent up behind the stick to attach the crotch strap. You could even get it tied into the bulkhead where the baggage compartment starts for extra strength.
Basically, the seat would be sitting on the entire strap, unnoticed beneath the seat cushion. Using SS or mild steel bent to conform to the seat pan shouldn't be that hard to do.
For a retro fit this would be a lot easier than getting into the bulkhead behind the stick.
Just an idea...
Basically, the seat would be sitting on the entire strap, unnoticed beneath the seat cushion. Using SS or mild steel bent to conform to the seat pan shouldn't be that hard to do.
For a retro fit this would be a lot easier than getting into the bulkhead behind the stick.
Just an idea...
F-304
Baggage compartment is behind seat pan in an RV-3. I don't see how that relates to a crotch strap.
Yes a steel plate, with the top part of it bent enough to allow for the head (or nut) of the 1/4" bolt, could be pop riveted to F-304. But the advantage of getting access behind F-304 is that the 1/4" bolt would go through F-304 too. Perhaps a sandwich of two 0.063 alu plates, with tops bent and a spacer between them would work too.
I just read the article in June Sport Aviation mag about "sub" belts. Main purpose appears to be preventing the lap bets from riding up over pelvis bones. I guess that "submarining" is another way of saying that.
Finn
Baggage compartment is behind seat pan in an RV-3. I don't see how that relates to a crotch strap.
Yes a steel plate, with the top part of it bent enough to allow for the head (or nut) of the 1/4" bolt, could be pop riveted to F-304. But the advantage of getting access behind F-304 is that the 1/4" bolt would go through F-304 too. Perhaps a sandwich of two 0.063 alu plates, with tops bent and a spacer between them would work too.
I just read the article in June Sport Aviation mag about "sub" belts. Main purpose appears to be preventing the lap bets from riding up over pelvis bones. I guess that "submarining" is another way of saying that.
Finn
I meant....
Make the strap wide enough to catch two rows of rivets starting at the point where the crotch strap would be and long enough to go back to the front baggage bulkhead. You could catch a bunch of rivets off the seat pan that way and I think It would be plenty strong for a crotch strap attach point.
Make the strap wide enough to catch two rows of rivets starting at the point where the crotch strap would be and long enough to go back to the front baggage bulkhead. You could catch a bunch of rivets off the seat pan that way and I think It would be plenty strong for a crotch strap attach point.
Chris Cooper
Active Member
Thanks everyone.
David Paule
Well Known Member
Make the strap wide enough to catch two rows of rivets starting at the point where the crotch strap would be and long enough to go back to the front baggage bulkhead. You could catch a bunch of rivets off the seat pan that way and I think It would be plenty strong for a crotch strap attach point.
While it could handle the forward part of the load, the upward part of the load could cause it to unzip. It should be tied into some of the bulkheads/ribs under the seat.
Dave
While it could handle the forward part of the load, the upward part of the load could cause it to unzip. It should be tied into some of the bulkheads/ribs under the seat.
Dave
+1
Perhaps there is a misconception that a crotch strap (sub belt) will hold you back from sliding forward. That is the lap belt's job. The crotch straps job is to hold the lap belt down in place around your pelvis and hips. Thus the major force on the crotch strap is up.
Finn
